sear: There is no mouse acceleration as far as I know, but the game is v-synced so there is some mouse lag introduced. You can try using your graphics control panel to force the game to not use v-sync, though this might introduce more issues.
No, the mouse acceleration is VERY noticeable. I have not used mouse acceleration (or "enhanced pointer precision" as Windows likes to call it) in years and it's throwing me off because of how inaccurate it is. I have experienced this in other games, and most of the time there is a hidden .ini setting that can turn it off.
Just in case, I tried forcing vsync off and there is no change.